Protective Coatings - Film Formation and Properties

0476127 - ÚMCH 2018 RIV CH eng M - Část monografie knihy
Zelenka, J. - Dušek, Karel - Wen, M.
Stress development in reactive coatings.
Protective Coatings - Film Formation and Properties. Cham: Springer International Publishing AG, 2017 - (Wen, M.; Dušek, K.), s. 241-267. ISBN 978-3-319-51625-7
Institucionální podpora: RVO:61389013
Klíčová slova: internal stress * stress measurement * cantilever deflection
Obor OECD: Polymer science

The chapter describes the internal stress development in reactive coatings during the process of film formation over a long period of time, e.g., well over 1000 h. Measurements of internal stress were made in situ using a cantilever method. Deflection of the cantilever was measured by two means: the traditional optical microscope method and a novel capacitive sensor method. The capacitive sensor approach was developed to determine the stress of coatings with higher film thickness. It offers unique advantages of high sensitivity and ease of testing multiple coatings simultaneously. The effects of acrylic polyol binder structure on the stress development of polyurethane coatings were examined in detail. The acrylic polyol binders are copolymers with defined structures synthesized by group transfer polymerization. The effects of copolymer structure, such as rigid vs. less rigid segments in the main chain, copolymer molecular weight, and crosslink density of the formed polyurethane network on the internal stress are discussed. Applying rigid segments in the polymeric chain leads to higher stress mainly in the rubbery region and around the vitrification point of the coating. Increasing the crosslinking density increases the plateau value of internal stress. Molecular weight of the copolymer does not affect the internal stress. Addition of a polyester polyol with low glass transition temperature can effectively lower the stress of a polyurethane coating. Addition of solvent to a polyurea coating with 100% solids was also investigated. Finally, the effect of baking, i.e., curing at an elevated temperature, was studied on a polyurea/polyurethane coating. These studies and the capacitive sensor approach developed will help understand long-term performance of reactive coatings.
Trvalý link: http://hdl.handle.net/11104/0277792